Department of Chemistry and Center of Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan.
J Colloid Interface Sci. 2011 Oct 15;362(2):354-66. doi: 10.1016/j.jcis.2011.07.011. Epub 2011 Jul 18.
Free-standing thin sheet form of mesoporous silica materials with perpendicular orientation is a much desired materials for its possible applications in catalysis, mask, and separation. A three component amphiphile system of sodium dodecyl sulfate/hexadecyltrimethylammonium bromide/pluronic-123(C(16)TMAB/SDS/P123) was employed to template the condensation of sodium silicates for the formation of SBA(⊥), a thin sheet of SBA-15 with perpendicular nanochannels. SBA(⊥) can be synthesized at SDS/C(16)TMAB=1.5 and T≥40°C and shows pH-dependent morphology. It has uniform pore size ∼9 nm, homogeneous sheet thickness in the range of 60-300 nm and dimension of several microns. We studied in details the structure and morphology of the SBA(⊥) with variation of three experimental parameters: the SDS/C(16)TMAB ratio, the temperature, and the pH condition in the synthetic gel. It is proposed that the mixed surfactants of SDS and C(16)TMAB form catanionic vesicle in which the P123 and silicates are condensed. The balanced interaction of P123/silicate with the narrow confinement under surfactant bi-layers of C(16)TMAB/SDS promoted the formation of perpendicular nanochannels. Low temperature and pH conditions favor stronger segregation of the PPO and PEO-oligosilicate segments in the SBA(⊥) structure which gives the basis of thickness control of the sheet. The control of structure and morphology are discussed with modern theory of microphase separation in block copolymers under confinement.
具有垂直取向的独立式介孔硅材料薄片是一种非常理想的材料，因为它可能在催化、掩蔽和分离方面有应用。我们使用了一种由十二烷基硫酸钠/十六烷基三甲基溴化铵/聚环氧丙烷-聚环氧乙烷-聚环氧丙烷三嵌段共聚物（SDS/C16TMAB/P123）组成的三组分两亲体体系来模板硅酸钠的缩合反应，从而形成 SBA(⊥)，这是一种具有垂直纳米通道的 SBA-15 薄片。SBA(⊥)可以在 SDS/C16TMAB=1.5 和 T≥40°C 的条件下合成，并表现出 pH 值依赖性形态。它具有均匀的孔径约 9nm，均匀的薄片厚度在 60-300nm 范围内，尺寸为数微米。我们详细研究了 SBA(⊥)的结构和形态，实验参数变化有三个：SDS/C16TMAB 比例、温度和合成凝胶中的 pH 值条件。我们提出 SDS 和 C16TMAB 的混合表面活性剂在其中缩合 P123 和硅酸盐的 CATANIONIC 囊泡。在 C(16)TMAB/SDS 双层表面活性剂的狭窄约束下，P123/硅酸盐的平衡相互作用促进了垂直纳米通道的形成。低温和低 pH 值条件有利于 PPO 和 PEO-寡硅酸盐段在 SBA(⊥)结构中的强分离，这为薄片厚度的控制提供了基础。我们还讨论了在受限条件下嵌段共聚物的微相分离现代理论对结构和形态的控制。
